Using Plate Discipline Metrics to Win Your Fantasy Baseball League (Part 2)

The quest to become the most informed fantasy owners in the universe continues. If you've been away for a bit, here are the links to our earlier pieces on a hitter's BABIP and then another on hard-hit rates. We then looked at pitchers and their SIERAs.

Last week housed the "Part One" primer on plate discipline metrics, investigating how often hitters swing and miss, as well as how often they swing at pitches outside of the strike zone. Now it's time for Part Two, where we'll explore more swing and contact metrics by way of a hypothetical at-bat.

Here is our reference for the article, let's pretend Nolan Arenado has this at-bat :

Pitch 1: Ball (Out of the zone).
Pitch 2: Strike (Swinging on a pitch out of the zone).
Pitch 3: Strike (Looking, pitch was in the zone).
Pitch 4: Ball (Out of the zone).
Pitch 5: Strike (Foul Ball on a pitch in the zone).
Pitch 6: Home Run (Pitch was in the zone).

It's hypothetical, so why not let him hit a homer? Okay, let's break this down.

Swing, O-Swing and Z-Swing Rates

Let's go one-by-one here:

Swing rate is how often a batter swings over number of pitches seen.

The hitter's swing rate here would be 50 percent, as he swung at three of the six pitches (the second, fifth and sixth).

O-Swing rate is the number of swings at pitches out of the zone over total pitches out of the zone. Also casually referred to as "chase rate", from how often a batter "chases" a pitch outside of the zone.

Go back to the six-pitch at-bat example, his O-Swing would be 33.3 percent thanks to swinging at one pitch out of the zone and taking two of them for balls.

Z-Swing rate is how often a player makes contact with pitches in the zone over total pitches in the zone. This speaks to how well a batter is doing at getting the bat on hittable pitches, as well as protecting the plate.

The reference at-bat would yield a 66.7 percent Z-swing rate thanks to swinging at pitches five and six, while not swinging at the third pitch which was in the zone.

On their own, these stats can't really provide too much insight. Once a player has a baseline then you can really identify changes - for better or worse.

Here are Nolan Arenado's respective Swing rate, O-Swing rate, and Z-Swing rate from 2015 and this season (as of May 13):

Year: Swing Rate -- O-Swing Rate -- Z-Swing Rate
2015: 54.2 percent -- 38.5 percent -- 74.2 percent
2016: 47.0 percent -- 31.6 percent -- 65.0 percent

What those numbers say about Arenado is that he's:
A) Swinging less in general.
B) Chasing less pitches out of the zone.
C) Swinging at less pitches in the zone.

It looks like something's brewing, as Arenado appears to be utilizing a more selective approach in the early going. It's also worth noting that a lower Z-swing rate can still mean a hitter is laying off pitches that, while strikes, cannot be squared up. Lastly, just because he is laying off more pitches doesn't mean he is more successful when he swings. These next stats can help fill that gap.

Contact, O-Contact, and Z-Contact

These rates speak to how often hitters make contact with said pitches. You'll see the same trend from the first set apply here:

Contact rate is the number of times contact was made with a pitch over total number of swings. This would be a 66.7 percent mark for the at-bat we've been using, with one swing-and-miss against a foul ball and the home run.

O-Contact rate is how often contact was made on pitches out of the zone over total swings out of zone. There are hitters who are notorious for succeeding even on pitches thrown out of the zone (Vladimir Guerrero comes to mind). Our at-bat would have a 0.0 percent O-Contact rate, with both the foul ball and home run coming on pitches in the zone.

Z-Contact rate is how often contact was made on pitches in the zone over total swings in the zone. Pitches in the strike zone are ideally more hittable, and our example provides a 100 percent Z-Contact rate.

Let's return to Mr. Arenado:

Year: Contact Rate -- O-Contact Rate -- Z-Contact Rate
2015: 80.3 percent -- 64.2 percent -- 90.9 percent
2016: 85.1 percent -- 71.4 percent -- 93.0 percent

Upward trends in every single category, including making contact with pitches out of the zone (when he deems them as pitches worth swinging at). He is exhibiting major growth in his fourth big league season, and not simply because of his league-leading 13 homers as of May 13.

The Big Picture

Now your analyses can run deeper than simply looking at whether a batter struck out, walked, or got a hit... Every single pitch provides a data point. As we said last time, why limit ourselves to judging an at-bat solely by the end result? The plate discipline leaderboard can be found here.

That leaderboard is a good starting point, but it is imperative that you pay attention to each player's traits. Don't compare a speedy contact hitter to a big power bat. Comparing a player's career rates to his current season can be intriguing, but the most useful comparison is usually their most recent season.

As always, no one number or set can tell the whole story. Perhaps a batter is seeing more off-speed or breaking pitches. Getting attacked with more inside pitches, low in the zone, etc. Maybe they're seeing the same pitches, but struggling with sliders this season. Fear not, as we'll get to all of those.

For now, these plate discipline tools can provide context for a hot or cold start, identify over and under-performances, and most importantly, win your fantasy baseball leagues. Speaking of winning tools, check out RotoBaller's new Risers and Fallers Identification Tool, which utilizes contact rates, along with BABIPs, to assist owners in their quest for dominance.